The inverse problem of a Gaussian convolution and its application to the finite size of the measurement chambers/detectors in photon and proton dosimetry.

abstract：:Histotripsy is an ultrasound ablation method that depends on the initiation of a cavitation bubble cloud to fractionate soft tissue. Although previous work has provided significant insight into the process of intrinsic threshold histotripsy, the majority of these studies have used highly focused (i.e. f-number  <  0.6...

journal_title：Physics in medicine and biology

authors： Vlaisavljevich E,Gerhardson T,Hall T,Xu Z

更新日期：2017-02-21 00:00:00

abstract：:K line x-ray fluorescence (KXRF) measurements of bone lead have emerged as a promising new biological marker of internal lead dose in epidemiological studies. Some disagreements exist, however, over the analysis of data at low levels of bone lead concentration. In this study, we performed 30 serial measurements on eac...

journal_title：Physics in medicine and biology

authors： Kim R,Aro A,Rotnitzky A,Amarasiriwardena C,Hu H

更新日期：1995-09-01 00:00:00

abstract：:Image-guided radiation therapy using implanted fiducial markers is a common solution for prostate localization to improve targeting accuracy. However, fiducials that are typically used for conventional photon radiotherapy cause large dose perturbations in patients who receive proton radiotherapy. A proposed solution h...

journal_title：Physics in medicine and biology

authors： Cheung J,Kudchadker RJ,Zhu XR,Lee AK,Newhauser WD

更新日期：2010-12-07 00:00:00

abstract：:In fully three-dimensional PET imaging, iterative image reconstruction techniques usually outperform analytical algorithms in terms of image quality provided that an appropriate system model is used. In this study we concentrate on the calculation of an accurate system model for the YAP-(S)PET II small animal scanner,...

journal_title：Physics in medicine and biology

authors： Cecchetti M,Moehrs S,Belcari N,Del Guerra A

更新日期：2013-10-07 00:00:00

abstract：:A novel meshless reconstruction algorithm for digital tomosynthesis (DT) is presented and assessed against experimental data. The algorithm does not require a three-dimensional grid or mesh allocation and performs a slice-by-slice reconstruction where each slice position can be chosen at runtime. The methodology is ba...

journal_title：Physics in medicine and biology

authors： Soloviev VY,Renforth KL,Dirckx CJ,Wells SG

更新日期：2020-04-20 00:00:00

abstract：:Dual-energy x-ray absorptiometry (DXA) is widely applied for estimating body fat. The percentage of body mass as fat (%fat) is predicted from a DXA-estimated R(ST) value defined as the ratio of soft tissue attenuation at two photon energies (e.g., 40 keV and 70 keV). Theoretically, the R(ST) concept depends on the mas...

journal_title：Physics in medicine and biology

authors： Wang Z,Heymsfield SB,Chen Z,Zhu S,Pierson RN

更新日期：2010-05-07 00:00:00

abstract：:This paper presents two 4D mathematical observer models for the detection of motion defects in 4D gated medical images. Their performance was compared with results from human observers in detecting a regional motion abnormality in simulated 4D gated myocardial perfusion (MP) SPECT images. The first 4D mathematical obs...

journal_title：Physics in medicine and biology

authors： Lee TS,Frey EC,Tsui BM

更新日期：2015-04-07 00:00:00

abstract：:In order to analyse the respective roles of ion concentration and fractional volume of the interstitial compartment as determinants of the impedance, Z, of renal medullary tissue, a model was needed in which both these factors could be varied independently. An array of blood cell suspensions ions in saline (different ...

journal_title：Physics in medicine and biology

authors： Niewiadomski W,Sadowski J,Badzyńska B,Rasmussen SN

更新日期：1990-11-01 00:00:00

abstract：:Silicon photomultipliers (SiPMs) are widely used in positron emission tomography (PET), however, SiPMs from different vendors vary in their performance characteristics. In addition, the specifications provided by the manufacturers are measured under different operating conditions and using different test setups, makin...

journal_title：Physics in medicine and biology

authors： Du J,Bai X,Cherry SR

更新日期：2019-08-07 00:00:00

abstract：:This paper contains the recommendations of the high dose rate (HDR) brachytherapy working party of the UK Institute of Physics and Engineering in Medicine (IPEM). The recommendations consist of a Code of Practice (COP) for the UK for measuring the reference air kerma rate (RAKR) of HDR (192)Ir brachytherapy sources. I...

journal_title：Physics in medicine and biology

authors： Bidmead AM,Sander T,Locks SM,Lee CD,Aird EG,Nutbrown RF,Flynn A,IPEM Working Party.

更新日期：2010-06-07 00:00:00

abstract：:This paper presents a description of tests carried out to compare the behaviour of five algorithms in inverse radiation therapy planning: (1) The Dynamically Penalized Likelihood (DPL), an algorithm based on statistical estimation theory; (2) an accelerated version of the same algorithm: (3) a new fast adaptive simula...

journal_title：Physics in medicine and biology

authors： Llacer J,Solberg TD,Promberger C

更新日期：2001-10-01 00:00:00

abstract：:Large volume tissue-equivalent proportional counters are of interest in radiation protection metrology, as the sensitivity in terms of counts per unit absorbed dose in these devices increases as the square of the counter diameter. Conventional solutions to the problem of maintaining a uniform electric field within a c...

journal_title：Physics in medicine and biology

authors： Verma PK,Waker AJ

更新日期：1992-10-01 00:00:00

abstract：:The design and performance of a dosimetric system for the irradiation of thin biological samples with therapeutic proton beams is reported. Protons with initial energies between 40 MeV and 250 MeV are degraded with polystyrene blocks of variable thickness in order to place the sample, an aqueous layer of 10 microm thi...

journal_title：Physics in medicine and biology

authors： Bashkirov V,Schulte RW

更新日期：2002-02-07 00:00:00

abstract：:Precision image-guided small animal radiotherapy is rapidly advancing through the use of dedicated micro-irradiation devices. However, precise modeling of these devices in model-based dose-calculation algorithms such as Monte Carlo (MC) simulations continue to present challenges due to a combination of very small beam...

journal_title：Physics in medicine and biology

authors： Granton PV,Verhaegen F

更新日期：2013-05-21 00:00:00

abstract：:Raman spectroscopy is a potentially important clinical tool for real-time diagnosis of disease and in situ evaluation of living tissue. The purpose of this article is to review the biological and physical basis of Raman spectroscopy of tissue, to assess the current status of the field and to explore future directions....

journal_title：Physics in medicine and biology

authors： Hanlon EB,Manoharan R,Koo TW,Shafer KE,Motz JT,Fitzmaurice M,Kramer JR,Itzkan I,Dasari RR,Feld MS

更新日期：2000-02-01 00:00:00

abstract：:We study the spatial distributions of beta(+)-activity produced by therapeutic beams of (3)He and (12)C ions in various tissue-like materials. The calculations were performed within a Monte Carlo model for heavy-ion therapy (MCHIT) based on the GEANT4 toolkit. The contributions from positron-emitting nuclei with T(1/2...

journal_title：Physics in medicine and biology

authors： Pshenichnov I,Larionov A,Mishustin I,Greiner W

更新日期：2007-12-21 00:00:00

abstract：:Recent research has suggested that endothelialization of vascular stents is crucial to reducing the risk of late stent thrombosis. With a resolution of approximately 10 microm, optical coherence tomography (OCT) may be an appropriate imaging modality for visualizing the vascular response to a stent and measuring the p...

journal_title：Physics in medicine and biology

authors： Bonnema GT,Cardinal KO,Williams SK,Barton JK

更新日期：2008-06-21 00:00:00

abstract：:Diffusion weighted magnetic resonance imaging offers a non-invasive tool to explore the three-dimensional structure of brain white matter in clinical practice. Anisotropic diffusion hardware phantoms are useful for the quantitative validation of this technique. This study provides guidelines on how to manufacture anis...

journal_title：Physics in medicine and biology

authors： Fieremans E,De Deene Y,Delputte S,Ozdemir MS,Achten E,Lemahieu I

更新日期：2008-10-07 00:00:00

abstract：:We tested the ability of a single Compton camera (CC) to produce 3-dimensional (3D) images of prompt gammas (PGs) emitted during the irradiation of a tissue-equivalent plastic phantom with proton pencil beams for clinical doses delivered at clinical dose rates. PG measurements were made with a small prototype CC place...

journal_title：Physics in medicine and biology

authors： Draeger E,Mackin D,Peterson S,Chen H,Avery S,Beddar S,Polf JC

更新日期：2018-01-30 00:00:00

abstract：:We propose and evaluate the performance of an improved preclinical positron emission tomography (PET) scanner design, referred to as Polaroid-PET, consisting of a detector equipped with a layer of horizontal Polaroid to filter scintillation photons with vertical polarization. This makes it possible to improve the spat...

journal_title：Physics in medicine and biology

authors： Sanaat A,Ashrafi-Belgabad A,Zaidi H

更新日期：2020-12-02 00:00:00

abstract：:Mean glandular dose (MGD) is the figure of merit to assess breast dose after a mammographic acquisition. The use of normalized MGD obtained from Monte Carlo computations with measured incident air kerma determines the MGD delivered to patients. The Geant4 Application for Tomographic Emission (GATE) toolkit is a modern...

journal_title：Physics in medicine and biology

authors： Myronakis ME,Zvelebil M,Darambara DG

更新日期：2013-04-07 00:00:00

abstract：:Kilo-voltage (KV) cone-beam computed tomography (CBCT) unit mounted onto a linear accelerator treatment system, often referred to as on-board imager (OBI), plays an increasingly important role in image-guided radiation therapy. While the FDK algorithm is currently used for reconstructing images from clinical OBI data,...

journal_title：Physics in medicine and biology

authors： Han X,Pearson E,Pelizzari C,Al-Hallaq H,Sidky EY,Bian J,Pan X

更新日期：2015-06-21 00:00:00

abstract：:The objective of this paper is to evaluate an iterative maximum likelihood (ML) cone-beam computed tomography (CBCT) reconstruction with total variation (TV) regularization with respect to the robustness of the algorithm due to data inconsistencies. Three different and (for clinical application) typical classes of err...

journal_title：Physics in medicine and biology

authors： Stsepankou D,Arns A,Ng SK,Zygmanski P,Hesser J

更新日期：2012-10-07 00:00:00

abstract：:This note describes a simple phantom which can be used to check the long term stability and accuracy of relative attenuation measurements made by near infra-red (NIR) spectrometers. The phantom has been calibrated, and the results of the calibration are shown to agree with theoretical predictions of the relative atten...

journal_title：Physics in medicine and biology

authors： Firbank M,Delpy DT

更新日期：1994-09-01 00:00:00

abstract：:An experimental determination of the energy correction factor for alanine/paraffin pellets in the 192Ir spectrum at varying distances from the source is presented. Alanine dosimeters were irradiated in water under full scatter conditions with a high dose rate (HDR) 192Ir source (Flexisource), using a dedicated holder....

journal_title：Physics in medicine and biology

authors： Schaeken B,Cuypers R,Goossens J,Van den Weyngaert D,Verellen D

更新日期：2011-10-21 00:00:00

abstract：:Proton, as well as other ion, beams applied by electro-magnetic deflection in pencil-beam scanning (PBS) are minimally perturbed and thus can be quantified a priori by their fundamental interactions in a medium. This a priori quantification permits an optimal reduction of characterizing measurements on a particular PB...

journal_title：Physics in medicine and biology

authors： Clasie B,Depauw N,Fransen M,Gomà C,Panahandeh HR,Seco J,Flanz JB,Kooy HM

更新日期：2012-03-07 00:00:00

abstract：:The lipid disordering effect of aspirin on the liposomal membrane of dipalmitoyl phosphatidyl choline has recently been studied using the fluorescence polarization method. From the anisotropy-temperature curve, we have calculated here the associated change in van't Hoff enthalpy. Since the fluorescence technique requi...

journal_title：Physics in medicine and biology

authors： De S,Ghosh AK,Basu R,Nandy P

更新日期：1996-03-01 00:00:00

abstract：:A variable Jacobian and weighted backprojection algorithm, used for medical CT, was adapted to perform CT reconstructions on data obtained with a dental panoramic x-ray unit. A detector array, fitted to the unit for the purpose of acquiring digital panoramic radiographs, was used to collect the data. Compensations wer...

journal_title：Physics in medicine and biology

authors： Lee MD,Waggener RG,McDavid WD,Dove SB,Welander U,Tronje G

更新日期：1992-12-01 00:00:00

abstract：:Over the course of radiation therapy, a patient's anatomy may change substantially. The relatively recent addition of frequent in-room imaging to assist with patient localization has provided a database of images that may be used to recalculate dose distributions for adaptive radiotherapy purposes. The TomoTherapy Hi-...

journal_title：Physics in medicine and biology

authors： Pukala J,Meeks SL,Bova FJ,Langen KM

更新日期：2011-12-21 00:00:00

abstract：:A near-field probe is described that enables high spatial resolution imaging with terahertz (THz) pulses. The spatial resolution capabilities of the system lie in the range of few microns and we demonstrate a resolution of 7 microm using broad-banded THz pulses with an intensity maximum near 0.5 THz. We present a stud...

journal_title：Physics in medicine and biology

authors： Federici JF,Mitrofanov O,Lee M,Hsu JW,Brener I,Harel R,Wynn JD,Pfeiffer LN,West KW

更新日期：2002-11-07 00:00:00